Action Points

Note that the study found that the independent predictors of 1-year target lesion failure were older age, insulin treatment, and smaller pre-procedure reference vessel diameter (less than 2.25 mm).

The Absorb bioresorbable vascular scaffold met preset expectations for its performance in diabetes patients, according to a study of pooled ABSORB data.

The rate of target lesion failure at 1 year after device implantation -- a composite endpoint of cardiac death, target vessel MI, and ischemia-driven target lesion revascularization -- was 8.3%, which bested the predetermined goal of 12.7% (P=0.0001), reported Dean J. Kereiakes, MD, of The Christ Hospital Heart and Vascular Center in Cincinnati, and colleagues.

Scaffold thrombosis occurred in 2.3% of the diabetic population, they also noted in JACC: Cardiovascular Interventions.

"This study was designed to support label expansion of Absorb in the US, and in this regard demonstrates efficacy and safety of Absorb bioresorbable vascular scaffold for the treatment of non-complex stable ischemic heart disease and stabilized acute coronary syndrome in patients with diabetes," the authors concluded.

Yet Ron Waksman, MD, of MedStar Washington Hospital Center in D.C., opposed the use of preset performance goals as the sole basis for granting expanded indication of a drug-eluting stent (DES) to patients with diabetes.

"Although the FDA may feel obliged to grant a diabetic indication to any DES stent that meets the performance goal due to the precedent established with Resolute, the question remains: Does it benefit diabetic patients?" he wrote in an accompanying editorial.

"Answering this question is particularly important now, considering that the diabetes indication can mislead physicians to believe that the stent has been shown to perform better than its competitors for this population when the reality is that the performance goal is more of a reflection of overall improved performance compared to first-generation stents and not necessarily an indication of how it performs in diabetic patients," Waksman argued.

He posed the question of whether the present findings support expanding the indication on Absorb's label to specifically include diabetics when the current labeling as written does not preclude use in them.

Regardless, "the available DES technology is not specifically designed to address lesions in diabetic patients," he concluded. "Granting the current DES, including Absorb, an indication for diabetics based on performance goals is not supported by science and can be potentially misinterpreted, especially considering the second-generation DES perform similarly to each other in randomized clinical trials. FDA should revisit the reliance on performance goal to support labeling indications, and instead encourage sponsors to address public health care issues related to approved second-generation DES as a class effect when they seek a specific indication on labeling as they did very successfully in the DAPT study."

"It is imperative that expanded indications on labeling of DES are scientifically valid. Industry, FDA, and investigators should reform the current process for indication expansion," the editorialist urged.

Although the ABSORB II, III, and JAPAN trials pooled in the analysis randomized patients to get Absorb or the Xience everolimus-eluting stent, the ABSORB EXTEND registry did not. And the lack of randomized assignment of patients with diabetes to treatment with either Absorb or Xience precluded any direct comparison between the two.

Kereiakes and colleagues performed a pre-specified pooling of the data for the 754 diabetes patients in the trials and registry, among whom 27.3% were insulin-treated.

They found that the independent predictors of 1-year target lesion failure were older age, insulin treatment, and smaller pre-procedure reference vessel diameter (less than 2.25 mm).

In fact, patients with small reference diameters had an "alarming" 6.5% scaffold thrombosis rate and a target lesion failure frequency of 15.5%.

Among diabetics with a large enough reference vessel diameter, target lesion failure at 1 year was similarly likely between Absorb and Xience recipients (6.6% versus 6.5%). Device thrombosis was still numerically more common in the Absorb arm (1.3% versus 0.4%), a persistent problem throughout the ABSORB trials.

"Despite being the largest analysis of patients with diabetes treated with Absorb bioresorbable vascular scaffold to date, this study remains underpowered to precisely evaluate low frequency events such as scaffold thrombosis," the investigators acknowledged.

In addition, their 1-year outcomes fell into a window when scaffold resorption is still incomplete.

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